CoCrFeNiMo0.2 high entropy alloy by laser melting deposition: Prospective material for low temperature and corrosion resistant applications

Abstract

In this paper, a Laser Metal Deposition (LMD) technique has been applied to fabricate CoCrFeNiMo0.2 high-entropy alloys (HEAs). The microstructure, corrosion behavior and mechanical properties of LMD CoCrFeNiMo0.2 HEAs prepared under different laser power have been investigated. It was observed that the laser power had significant effects on the columnar crystal morphology in LMD CoCrFeNiMo0.2 HEAs. When increasing the laser power, the temperature gradient would decrease, leading to larger crystal size of columnar grains. The tensile properties at 293 K of the LMD CoCrFeNiMo0.2 HEAs could be adjusted by changing the laser power, which was corresponded to the changes of microstructure. With a decrease in temperature from 293 K to 77 K, the tensile strength and tensile ductility of the LMD 1400 W CoCrFeNiMo0.2 HEAs remarkably improved by ~70% and ~28%, to 928 MPa and 60%, respectively. In both 3.5 wt% NaCl solution and 1 mol/L H2SO4 solution, the CoCrFeNiMo0.2 exhibited higher corrosion resistance than 304 stainless steel substrate, CoCrFeNi and even lower corrosion current density than 316L stainless steel.